We have created a low cost (<$150) operant training box, using open source tools and software. Operant training is a highly valuable form of behavioral testing that can assay motivation, impulsiveness, anxiety, depression, addiction, and many other behavioral processes. Unfortunately, most commerical suppliers provide chambers that cost on the order of $5-10K per chamber, once all software and hardware is accounted for. This is prohibitively expensive for many researchers, so we would like to develop a low cost solution that will allow our selves, our collaborators, and any other interested researchers access to this form of behavioral testing. In the past year, we have finalized design of our operant chamber, begun testing it for training mice on operant responding for food, and published a first paper outlining how to build this device. In the current year, we are preparing a new version of the device that is based around a pellet dispenser, and can be used to regulate feeding in laboratory mice, as well as investigate operant behavior. We are currently preparing a manuscript on the new version as well.